Huawei H12-821_V1.0 - HCIP-Datacom-Core Technology V1.0

The default sending interval for BFD (Bidirectional Forwarding Detection) control packets is 100 milliseconds. This interval ensures rapid detection of link faults, providing fast failover and minimizing downtime in network operations ​.

Internet– Thiscommunity attribute allows a route to be advertised to any BGP peer, including EBGP and IBGP. This is the default behavior if no other restrictive community is attached.

No_Advertise– Prevents the route from being advertised toanypeer.

No_Export– Prevents the route from being advertised toEBGP peers.

No_Export_Subconfed– Restricts the route from being advertisedoutside the sub-ASin a confederation.

Reference from Huawei HCIP-Datacom-Core Technology Study Guide:

“The Internet community attribute allows unrestricted advertisement of a route. Other community attributes like No_Advertise and No_Export limit route propagation.”

(Chapter: BGP Community Attributes – Section: Well-known Communities)

On Huawei devices, multiple BGP processes can be configured on the same router, but they are typically used for specific use cases such as multi-instance deployments or virtual routers. This flexibility is supported by Huawei's routing protocols ​.

1. Understanding Prefix List Configuration:

The command ip ip-prefix huawei index 10 permit 10.1.1.0 24 greater-equal 26 defines a prefix filter:

The base prefix is 10.1.1.0/24.

The greater-equal 26 condition specifies that the mask length of matching prefixes must beat least 26 bits.

If the less-equal parameter is not explicitly defined, the default value is32, meaning the longest possible mask length for IPv4.

2. Explanation of Values:

greater-equal-value: Specifies the minimum mask length. In this case, the value is26.

less-equal-value: Specifies the maximum mask length. Since it is not explicitly configured, the default value is32.

3. Summary:

greater-equal-value = 26

less-equal-value = 32

Huawei HCIA-Datacom Study Guide, Chapter "IP Prefix List Configuration."

ï‚· IS-IS Overview: Intermediate System to Intermediate System (IS-IS) is a link-state routing protocol. Routers exchangeLink State Packets (LSPs)to maintain a synchronized link-state database. These LSPs are categorized intoLevel-1 LSPs(intra-area routing) andLevel-2 LSPs(inter-area routing). Both types share the same packet format.

HCIP-Datacom-Core Technology Training Material (IS-IS LSPs and Packet Structure)​​.

ï‚· LSP ID Format: The LSP ID uniquely identifies each LSP and ensures accurate routing information. It comprises the following components:

System ID (C): A 6-byte identifier assigned to each router, derived from the router's NET (Network Entity Title). This identifier ensures unique identification of routers within the IS-IS domain.

Pseudonode ID (B): Assigned when a router acts as a Designated Intermediate System (DIS) on a broadcast network. It differentiates LSPs generated by the DIS from other routers.

LSP Number (A): A 1-byte field indicating the sequence number of the LSP. It helps distinguish multiple LSPs generated by the same router for the same level.

A is correct– Confederations arespecifically designed for large-scale BGP deploymentswhere a full IBGP mesh is impractical.

B is correct– Sub-ASs within a confederation establishEBGP-like connectionsbetween each other but behave like IBGP within the overall AS. These sub-ASsdo not require full-mesh inside the confederation, but EBGP rules are followed between sub-ASs.

C is false–Not all devices need to be reconfigured. Devices within the same sub-AS retain normal IBGP behavior and minimal changes.

D is correct– Confederation istransparent to external peers, so thelogical topology remains the samefrom outside the AS.

Reference from Huawei HCIP-Datacom-Core Technology Study Guide:

“BGP confederation divides an AS into multiple sub-ASs. EBGP-like sessions are established between sub-ASs, while reducing IBGP mesh complexity. The external AS still sees the AS as one unit.”

(Chapter: BGP Scalability Enhancements – Section: Confederation)

ï‚· ACL Matching in Huawei Routers:

Access Control Lists (ACLs) are used to filter packets based on specific criteria, such as source/destination IP, ports, or protocols.

When a packet arrives, the Huawei router processes it against the configured ACL rules to decide whether to permit or deny the packet.

IGMP Version Mismatch

If the IGMP snooping version on the device is earlier than the IGMP version on user hosts, the device may fail to parse IGMP Report messages correctly. As a result, the device forwards these messages only to router ports without generating group member ports or forwarding entries.

Consequently, users cannot receive multicast data.

HCIP-Datacom-Core Reference

Multicast and IGMP snooping behaviors under mismatched conditions are described in the multicast configuration chapters​​.

Route summarization in OSPF is restricted to specific routers: Area Border Routers (ABRs) and Autonomous System Boundary Routers (ASBRs). These devices perform summarization to reduce routing table size and minimize advertised routing information between areas or across AS boundaries. Regular routers cannot perform route summarization, making this statement false ​.

In the topology, SWB's GE0/0/2 is the Root Port because it has the least cost path to the Root Bridge (SWA). SWC's GE0/0/1 is the Designated Port because it forwards traffic to SWA while maintaining the shortest path to the Root Bridge. This setup ensures efficient traffic flow in the spanning tree topology ​.